What a waste of good brew.
Assuming it was good, anyway....
Last year, we had a rash of incidents in our group, ranging from altercations with motorcyclists, empty water bottles, full soda bottles, FULL liter-size water bottles thrown from a car going 60-65 mph (thankfully they missed the target), and a half-full 1/2 gallon jug of orange juice (broke on impact, of course). Yellers are a normal occurance -- we wave exaggeratedly...and I usually mutter "a-hole" for emphasis.
After two or so incidents, I emailed a police commander I work with and asked him to please relay word of the problem to other law enforcement agencies (Sheriff and CHP), which he did. I also told him our regular ride routes on certain days and where you will generally find cyclists out & about. Shortly thereafter, we noticed more patrol cars on those roads.
In the wee-season this year, we managed to get half a license plate number from a yeller's car (I think they threw something too), called the CHP with our cell phones, and they showed up in about 5 minutes to take a report - he happened to be in the area.
The response from law enforcement around here has been amazing, and it has really strengthened our relationship with them. One officer finds time to catch speeders while he patrols -- waves to us from his ticket pad as we pass.
This spring/summer season has been better, but there was a verbal altercation with some knot-heads in a van a few weeks ago.
Be careful out there, but for those who this thread is scaring -- don't let the idiots win. Get out, ride your bike, and remember to smile big. 
~BikeMomma
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein